The present invention relates generally to door assemblies for shelter structures and shelter structures including door assemblies, and in particular, to an improved door assembly and shelter including such a door assembly in which the door assembly is constructed to be essentially free standing (i.e. otherwise free of any rigid connection to the outer frame of the shelter). Such a construction is an improvement over the prior art for several reasons, including but not limited to, the ability to maintain satisfactory alignment of the door assembly and to permit extension and retraction of the flexible material comprising the door, as well as to improve adjustability to accommodate for varying ground and/or surface conditions.
Shelter structures with and without door assemblies are known. One such example of a shelter structure with a door is described and illustrated in Canadian Patent No. 2,051,998. However, it is believed that the shelter door system described and illustrated in this '998 patent has deficiencies. As but one example, it is believed that a door assembly that is rigidly connected to the outer frame will tend to more easily torque, thereby preventing smooth retraction and extension of the door itself during all conditions.
The foregoing problem may occur most frequently during conditions that may tend to twist, bend or degrade the structural integrity of the shelter, such as during windy conditions that act upon the constructed structure or conditions that result in variances (in surface make-up or height) of the ground, thereby resulting in what would be an undesirable twisting or torquing of the door assembly and preventing or reducing the likelihood of the door from retracting or extending efficiently and/or properly. Surely other conditions may also play a part in exacerbating this twisting or torque problem, but the problems themselves are not material to the present invention. What is material to the present invention is a construction, arrangement and method to reduce and/or eliminate such undesirable consequences, among other objectives.
Thus, it is believed that further advances in the art are desirable. For example, it would be desirable and advantageous to design a door assembly and shelter that utilizes such a door assembly that reduces and/or eliminates the aforementioned twisting and/or torquing of the door assembly. In addition, it would be desirable and advantageous to provide all of the foregoing in a tubular structure that is not overly expensive to manufacture and is reasonably priced to consumers, all while overcoming the aforementioned deficiencies and achieving the aforementioned and below mentioned objectives.